As the functional components of integrated circuit (IC) have decreased in size, the number of functions integrated onto ICs has commensurately increased. These functions may be separated into functional units or functional modules, each of which may serve a different purpose. These functional modules may be digital, analog, or mixed-signal. Additionally, some ICs may implement a voltage regulator on the same die as the functional modules to power the functional modules.
Some ICs are required to meet stringent requirements for functional safety. By way of example, safety is a critical objective for systems that may cause harm if component or system failure is not mitigated, such as in safety-critical applications in the automotive domain. Accordingly, functional safety is increasingly requiring continuous monitoring of the analog and mixed-signal circuits in safety-critical applications without disturbing the normal functionality of the IC. In digital IC testing, some structured test methods such as scan-test and built-in self-testing have already become common practice. However, continuous monitoring for functional safety of analog and mixed-signal circuits during operation faces several challenges. In particular, defects in and an aging effect of analog circuits are difficult to detect without disturbing the normal functionality of the IC.